<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
        <h1><a href="../default.html">返回主页</a></h1>
    <select id="province">
        <option value="-1">请选择</option>
    </select>
    <select id="city"></select>
    <select id="country"></select>
    <script>
   var provinceArr=['上海','江苏','河北'];
        var cityArr = [
            ['上海市'],
            ['苏州市','南京市','扬州市'],
            ['石家庄','秦皇岛','张家口'],
        ];
        var countryArr=[
            [
                ['黄浦区','静安区','长宁区','浦东区']
            ],
            [
                ['虎丘区','吴中区','相城区','姑苏区','吴江区'],
                ['玄武区','秦淮区','建邺区','鼓楼区','浦口区'],
                ['邗江区','广陵区','江都区']
            ],
            [
                ['长安区','桥西区','新华区','井陉矿区'],
                ['海港区','山海关区','北戴河区','抚宁区'],
                ['桥东区','桥西区','宣化区','下花园区']
            ],
        ];
        
        function createOption(obj,data){
            for(var i in data){
                var op = new Option(data[i],i);
                obj.options.add(op);
            }
        }
        var porvince = document.getElementById('province');
        createOption(porvince,provinceArr);
        var city = document.getElementById('city');
        province.onchange=function(){
            city.options.length=0;
            createOption(city,cityArr[porvince.value]);
        }
        var country = document.getElementById('country');
        city.onchange=function(){
            country.options.length=0;
            createOption(country,countryArr[porvince.value][city.value]);
        }
        province.onchange = function(){
            city.options.length=0;
            createOption(city,cityArr[province.value]);
            if(province.value>=0){
                city.onchange();
            }else{
                country.options.length=0;
            }
        }
        
    </script>
     
</body>
</html>